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71.
基于神经网络的建筑物沉降原因分析 总被引:1,自引:0,他引:1
在我们应用回归方法对建筑物沉降原因分析及沉降趋势的预测中,由于实际情况的复杂性及主观认识的局限性,这样所得的结果含有较多的人为因素,可能会与实际情况有所差异。针对这种情况,讨论了应用神经网络方法来发现和验证引起建筑物沉降的因素及对沉降趋势的预测。实例表明,该方法能取得较好的效果。 相似文献
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以山西省祁县依法管理工程抗震设防要求为例,论述了强制性审核、确定一般工业、民用建设工程抗震设防要求的重要性及其深远意义。结合工作实际.总结了部分依法行政、规范管理和落实抗震设防要求的经验。 相似文献
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When sediment grains are transported as bed load in overland flow, there is a net transfer of momentum from the flow to the grains. When these grains collide with other grains, whether on the bed or in the flow, streamwise flow velocity decreases and resistance to flow increases. Resistance to flow generated in this manner is termed bed‐load transport resistance. Resistance to flow f over a plane bed may be partitioned into grain resistance fg and bed‐load transport resistance fbt. We use the symbols fbtf and fbtm to denote fbt for flows over fixed beds and over mobile beds, respectively, and we compute the effect of bed mobility on flow resistance fmob by subtracting fbtf from fbtm. The data for this study come from 54 flume experiments with fixed beds and 38 with mobile beds. On average fmob is approximately equal to half of fbtm, which is about one‐quarter of f. Hence, fmob is about one‐tenth of f. Predictive equations are developed for fbtf, fbtm and fmob using dimensional analysis to identify the relevant independent variables and regression analysis to evaluate the coefficients associated with these variables. Values of fmob are always positive which implies that mobile beds offer greater resistance to flow than do fixed beds. Evidently bed‐load grains colliding with mobile beds lose more momentum to the bed than do grains colliding with fixed beds. In other words, grain collisions with mobile beds are less elastic than those with fixed beds. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
74.
格尔木井水温异常特征及其与地震关系分析 总被引:1,自引:1,他引:1
简要介绍了格尔木井水温动态观测的环境与条件,在研究正常动态特征和影响因素的基础上,对水温异常的映震关系进行了分析,并成功地进行了一次短临地震趋势预测。探讨了水温异常的形成原因。 相似文献
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通过2个工程实例分析了沉管灌注桩出现大面积断桩的原因是由于后期基坑开挖不当造成的,并提出了预防断桩出现的一些措施以及对断桩的处理补救措施。 相似文献
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The role of baseflow in dissolved solids delivery to streams in the Upper Colorado River Basin
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Christine A. Rumsey Matthew P. Miller Gregory E. Schwarz Robert M. Hirsch David D. Susong 《水文研究》2017,31(26):4705-4718
Salinity has a major effect on water users in the Colorado River Basin, estimated to cause almost $300 million per year in economic damages. The Colorado River Basin Salinity Control Program implements and manages projects to reduce salinity loads, investing millions of dollars per year in irrigation upgrades, canal projects, and other mitigation strategies. To inform and improve mitigation efforts, there is a need to better understand sources of salinity to streams and how salinity has changed over time. This study explores salinity in the baseflow fraction of streamflow, assessing whether groundwater is a significant contributor of dissolved solids to streams in the Upper Colorado River Basin (UCRB). Chemical hydrograph separation was used to estimate baseflow discharge and baseflow dissolved solids loads at stream gages (n = 69) across the UCRB. On average, it is estimated that 89% of dissolved solids loads originate from the baseflow fraction of streamflow, indicating that subsurface transport processes play a dominant role in delivering dissolved solids to streams in the UCRB. A statistical trend analysis using weighted regressions on time, discharge, and season was used to evaluate changes in baseflow dissolved solids loads in streams (n = 27) from 1986 to 2011. Decreasing trends in baseflow dissolved solids loads were observed at 63% of streams. At the three most downstream sites, Green River at Green River, UT, Colorado River at Cisco, UT, and the San Juan River near Bluff, UT, baseflow dissolved solids loads decreased by a combined 823,000 metric tons (mT), which is approximately 69% of projected basin‐scale decreases in total dissolved solids loads as a result of salinity control efforts. Decreasing trends in baseflow dissolved solids loads suggest that salinity mitigation projects, landscape changes, and/or climate are reducing dissolved solids transported to streams through the subsurface. Notably, the pace and extent of decreases in baseflow dissolved solids loads declined during the most recent decade; average decreasing loads during the 2000s (28,200 mT) were only 54% of average decreasing loads in the 1990s (51,700 mT). 相似文献